1. Technical Field
The present disclosure relates to carbon nanotube structures and methods for making the same and, particularly, to a carbon nanotube precursor, a carbon nanotube film and a method for making the same.
2. Description of Related Art
Carbon nanotubes are novel carbonaceous material and have received a great deal of interest since the early 1990s. The carbon nanotubes are electrically conductive, chemically stable, and each can have a very small diameter (much less than 100 nanometers) and large aspect ratios (length/diameter). Thus, carbon nanotubes have become a significant focus of research and development for use in electron emitting devices, sensors, transistors, and other devices.
Generally, the carbon nanotubes prepared by conventional methods are in particle or powder forms. The particle or powder-shaped carbon nanotubes limit the applications in which they can be used. Thus, preparation of macro-scale carbon nanotube structures, such as carbon nanotube films, has attracted attention.
A conventional method for making a carbon nanotube film includes the steps of providing a growing substrate; forming a catalyst layer on the growing substrate; providing a reacting furnace, placing the growing substrate with the catalyst layer into the reacting furnace; introducing a carbonaceous gas, and heating the reacting furnace to grow the carbon nanotube film. However, the carbon nanotube film made by the above-described method is formed on the growing substrate and does not have a free-standing structure. Further, the carbon nanotubes in the carbon nanotube film are always entangled with each other and disorderly distributed therein. Thus, the excellent properties of the carbon nanotubes are poorly utilized.
A method for making a nanofiber film includes arranging nanofibers to provide a substantially parallel nanofiber array having a degree of inter-fiber connectivity within the nanofiber array, and drawing said nanofibers from the nanofiber array as a ribbon or sheet without substantially twisting the ribbon or sheet. The nanofiber array has a columnar shape and can be a carbon nanotube array.
When the nanofibers are drawn from the nanofiber array to form the ribbon or sheet, the width of the nanofiber ribbon or sheet is inevitably affected by the columnar nanofiber array, thus the nanofiber ribbon or sheet cannot have a uniform width, thereby it is not entirely suitable for industrial applications.
What is needed, therefore, is a carbon nanotube precursor, a carbon nanotube film and a method for making the same, wherein the carbon nanotube film has a uniform width.